LinuxLists.cc - [PATCH v2 00/13] refactor Kconfig to consolidate KEXEC and CRASH options

2023-06-19 15:03:43

Subject: [PATCH v2 00/13] refactor Kconfig to consolidate KEXEC and CRASH options

The Kconfig is refactored to consolidate KEXEC and CRASH options from
various arch/<arch>/Kconfig files into new file kernel/Kconfig.kexec.

The Kconfig.kexec is now a submenu titled "Kexec and crash features"
located under "General Setup".

The following options are impacted:

- KEXEC
- KEXEC_FILE
- KEXEC_SIG
- KEXEC_SIG_FORCE
- KEXEC_BZIMAGE_VERIFY_SIG
- KEXEC_JUMP
- CRASH_DUMP

Over time, these options have been copied between Kconfig files and
are very similar to one another, but with slight differences.

The following architectures are impacted by the refactor (because of
use of one or more KEXEC/CRASH options):

- arm
- arm64
- ia64
- loongarch
- m68k
- mips
- parisc
- powerpc
- riscv
- s390
- sh
- x86

More information:

In the patch series "crash: Kernel handling of CPU and memory hot
un/plug"

https://lore.kernel.org/lkml/[email protected]/

the new kernel feature introduces the config option CRASH_HOTPLUG.

In reviewing, Thomas Gleixner requested that the new config option
not be placed in x86 Kconfig. Rather the option needs a generic/common
home. To Thomas' point, the KEXEC and CRASH options have largely been
duplicated in the various arch/<arch>/Kconfig files, with minor
differences. This kind of proliferation is to be avoid/stopped.

https://lore.kernel.org/lkml/875y91yv63.ffs@tglx/

To that end, I have refactored the arch Kconfigs so as to consolidate
the various KEXEC and CRASH options. Generally speaking, this work has
the following themes:

- KEXEC and CRASH options are moved into new file kernel/Kconfig.kexec
- These items from arch/Kconfig:
CRASH_CORE KEXEC_CORE KEXEC_ELF HAVE_IMA_KEXEC
- These items from arch/x86/Kconfig form the common options:
KEXEC KEXEC_FILE KEXEC_SIG KEXEC_SIG_FORCE
KEXEC_BZIMAGE_VERIFY_SIG KEXEC_JUMP CRASH_DUMP
- The crash hotplug series appends CRASH_HOTPLUG to Kconfig.kexec
NOTE: PHYSICAL_START could be argued to be included in this series.
- The Kconfig.kexec is now a submenu titled "Kexec and crash features"
- The Kconfig.kexec is now listed in "General Setup" submenu from
init/Kconfig
- To control the main common options, new options ARCH_SUPPORTS_KEXEC,
ARCH_SUPPORTS_KEXEC_FILE and ARCH_SUPPORTS_CRASH_DUMP are introduced.
NOTE: The existing ARCH_HAS_KEXEC_PURGATORY remains unchanged.
- To account for the slight differences, new options ARCH_SELECTS_KEXEC,
ARCH_SELECTS_KEXEC_FILE and ARCH_SELECTS_CRASH_DUMP are used to
elicit the same side effects as the original arch/<arch>/Kconfig
files for KEXEC and CRASH options.

An example, 'make menuconfig' illustrating the submenu:

> General setup > Kexec and crash features
[*] Enable kexec system call
[*] Enable kexec file based system call
[*] Verify kernel signature during kexec_file_load() syscall
[ ] Require a valid signature in kexec_file_load() syscall
[ ] Enable bzImage signature verification support
[*] kexec jump
[*] kernel crash dumps
[*] Update the crash elfcorehdr on system configuration changes

The three main options are KEXEC, KEXEC_FILE and CRASH_DUMP. In the
process of consolidating these options, I encountered slight differences
in the coding of these options in several of the architectures. As a
result, I settled on the following solution:

- Each of three main options has a 'depends on ARCH_SUPPORTS_<option>'
statement: ARCH_SUPPORTS_KEXEC, ARCH_SUPPORTS_KEXEC_FILE,
ARCH_SUPPORTS_CRASH_DUMP.

For example, the KEXEC_FILE option has a 'depends on
ARCH_SUPPORTS_KEXEC_FILE' statement.

- The boolean ARCH_SUPPORTS_<option> in effect allows the arch to
determine when the feature is allowed. Archs which don't have the
feature simply do not provide the corresponding ARCH_SUPPORTS_<option>.
For each arch, where there previously were KEXEC and/or CRASH
options, these have been replaced with the corresponding boolean
ARCH_SUPPORTS_<option>, and an appropriate def_bool statement.

For example, if the arch supports KEXEC_FILE, then the
ARCH_SUPPORTS_KEXEC_FILE simply has a 'def_bool y'. This permits the
KEXEC_FILE option to be available.

If the arch has a 'depends on' statement in its original coding
of the option, then that expression becomes part of the def_bool
expression. For example, arm64 had:

config KEXEC
depends on PM_SLEEP_SMP

and in this solution, this converts to:

config ARCH_SUPPORTS_KEXEC
def_bool PM_SLEEP_SMP

- In order to account for the differences in the config coding for
the three common options, the ARCH_SELECTS_<option> is used.
This options has a 'depends on <option>' statement to couple it
to the main option, and from there can insert the differences
from the common option and the arch original coding of that option.

For example, a few archs enable CRYPTO and CRYTPO_SHA256 for
KEXEC_FILE. These require a ARCH_SELECTS_KEXEC_FILE and
'select CRYPTO' and 'select CRYPTO_SHA256' statements.

Illustrating the option relationships:

For KEXEC:
ARCH_SUPPORTS_KEXEC <- KEXEC <- ARCH_SELECTS_KEXEC

KEXEC # in Kconfig.kexec
ARCH_SUPPORTS_KEXEC # in arch/<arch>/Kconfig, as needed
ARCH_SELECTS_KEXEC # in arch/<arch>/Kconfig, as needed

For KEXEC_FILE:
ARCH_SUPPORTS_KEXEC_FILE <- KEXEC_FILE <- ARCH_SELECTS_KEXEC_FILE

KEXEC_FILE # in Kconfig.kexec
ARCH_SUPPORTS_KEXEC_FILE # in arch/<arch>/Kconfig, as needed
ARCH_SELECTS_KEXEC_FILE # in arch/<arch>/Kconfig, as needed

For CRASH:
ARCH_SUPPORTS_CRASH_DUMP <- CRASH_DUMP <- ARCH_SELECTS_CRASH_DUMP

CRASH_DUMP # in Kconfig.kexec
ARCH_SUPPORTS_CRASH_DUMP # in arch/<arch>/Kconfig, as needed
ARCH_SELECTS_CRASH_DUMP # in arch/<arch>/Kconfig, as needed

To summarize, the ARCH_SUPPORTS_<option> permits the <option> to be
enabled, and the ARCH_SELECTS_<option> handles side effects (ie.
select statements).

Examples:
A few examples to show the new strategy in action:

===== x86 (minus the help section) =====
Original:
config KEXEC
bool "kexec system call"
select KEXEC_CORE

config KEXEC_FILE
bool "kexec file based system call"
select KEXEC_CORE
select HAVE_IMA_KEXEC if IMA
depends on X86_64
depends on CRYPTO=y
depends on CRYPTO_SHA256=y

config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE

config KEXEC_SIG
bool "Verify kernel signature during kexec_file_load() syscall"
depends on KEXEC_FILE

config KEXEC_SIG_FORCE
bool "Require a valid signature in kexec_file_load() syscall"
depends on KEXEC_SIG

config KEXEC_BZIMAGE_VERIFY_SIG
bool "Enable bzImage signature verification support"
depends on KEXEC_SIG
depends on SIGNED_PE_FILE_VERIFICATION
select SYSTEM_TRUSTED_KEYRING

config CRASH_DUMP
bool "kernel crash dumps"
depends on X86_64 || (X86_32 && HIGHMEM)

config KEXEC_JUMP
bool "kexec jump"
depends on KEXEC && HIBERNATION
help

becomes...
New:
config ARCH_SUPPORTS_KEXEC
def_bool y

config ARCH_SUPPORTS_KEXEC_FILE
def_bool X86_64 && CRYPTO && CRYPTO_SHA256

config ARCH_SELECTS_KEXEC_FILE
def_bool y
depends on KEXEC_FILE
select HAVE_IMA_KEXEC if IMA

config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE

config ARCH_SUPPORTS_KEXEC_JUMP
def_bool y

config ARCH_SUPPORTS_CRASH_DUMP
def_bool X86_64 || (X86_32 && HIGHMEM)

===== powerpc (minus the help section) =====
Original:
config KEXEC
bool "kexec system call"
depends on PPC_BOOK3S || PPC_E500 || (44x && !SMP)
select KEXEC_CORE

config KEXEC_FILE
bool "kexec file based system call"
select KEXEC_CORE
select HAVE_IMA_KEXEC if IMA
select KEXEC_ELF
depends on PPC64
depends on CRYPTO=y
depends on CRYPTO_SHA256=y

config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE

config CRASH_DUMP
bool "Build a dump capture kernel"
depends on PPC64 || PPC_BOOK3S_32 || PPC_85xx || (44x && !SMP)
select RELOCATABLE if PPC64 || 44x || PPC_85xx

becomes...
New:
config ARCH_SUPPORTS_KEXEC
def_bool PPC_BOOK3S || PPC_E500 || (44x && !SMP)

config ARCH_SUPPORTS_KEXEC_FILE
def_bool PPC64 && CRYPTO=y && CRYPTO_SHA256=y

config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE

config ARCH_SELECTS_KEXEC_FILE
def_bool y
depends on KEXEC_FILE
select KEXEC_ELF
select HAVE_IMA_KEXEC if IMA

config ARCH_SUPPORTS_CRASH_DUMP
def_bool PPC64 || PPC_BOOK3S_32 || PPC_85xx || (44x && !SMP)

config ARCH_SELECTS_CRASH_DUMP
def_bool y
depends on CRASH_DUMP
select RELOCATABLE if PPC64 || 44x || PPC_85xx

Testing Approach and Results

There are 388 config files in the arch/<arch>/configs directories.
For each of these config files, a .config is generated both before and
after this Kconfig series, and checked for equivalence. This approach
allows for a rather rapid check of all architectures and a wide
variety of configs wrt/ KEXEC and CRASH, and avoids requiring
compiling for all architectures and running kernels and run-time
testing.

As such, I developed the following script to compare the before and
after of 'make olddefconfig'. The new symbols introduced by this
series are filtered out, but otherwise the config files are PASS
only if they were equivalent, and FAIL otherwise.

The script performs the test by doing the following:

# Obtain the "golden" .config output for given config file
# Reset test sandbox
git checkout master
git branch -D test_Kconfig
git checkout -B test_Kconfig master
make distclean
# Write out updated config
cp -f <config file> .config
make ARCH=<arch> olddefconfig
# Track each item in .config, LHSB is "golden"
scoreboard .config

# Obtain the "changed" .config output for given config file
# Reset test sandbox
make distclean
# Apply this Kconfig series
git am <this Kconfig series>
# Write out updated config
cp -f <config file> .config
make ARCH=<arch> olddefconfig
# Track each item in .config, RHSB is "changed"
scoreboard .config

# Determine test result
# Filter-out new symbols introduced by this series
# Filter-out symbol=n which not in either scoreboard
# Compare LHSB "golden" and RHSB "changed" scoreboards and issue PASS/FAIL

The script was instrumental during the refactoring of Kconfig as it
continually revealed problems. The end result being that the solution
presented in this series passes all configs as checked by the script.

Regards,
eric

---
v2: 19jun2023
- The ARCH_HAS_ and ARCH_SUPPORTS_ combination was found to be
too similar. Renamed these two new options as such:
ARCH_HAS_<option> ---> ARCH_SUPPORTS_<option>
ARCH_SUPPORTS_<option> ---> ARCH_SELECTS_<option>
Per Kees Cook, Michael Ellerman
NOTE: ARCH_HAS_KEXEC_PURGATORY was left as-is, as that is what
it is prior to this series.
Updated this cover letter to reflect the same.
- Some minor cleaning up of the help sections, per Zhen Lei and
Alexander Gordeev.
- Removed the MODULE_SIG_FORMAT dependency from KEXEC_SIG in
kernel/Kconfig.kexec. Only s390 had it prior to this series.
See also commit message in
"s390/kexec: refactor for kernel/Kconfig.kexec"
- Added to Kconfig.kexec the KEXEC_IMAGE_VERIFY_SIG from arm64,
per Zhen Lei.
- Fixed the powerpc ARCH_SUPPORTS_KEXEC_FILE conversion, per
Michael Ellerman.

v1: 12jun2023
https://lore.kernel.org/lkml/[email protected]/
- Initial
- Based on 6.4.0-rc6

---

Eric DeVolder (13):
kexec: consolidate kexec and crash options into kernel/Kconfig.kexec
x86/kexec: refactor for kernel/Kconfig.kexec
arm/kexec: refactor for kernel/Kconfig.kexec
ia64/kexec: refactor for kernel/Kconfig.kexec
arm64/kexec: refactor for kernel/Kconfig.kexec
loongarch/kexec: refactor for kernel/Kconfig.kexec
m68k/kexec: refactor for kernel/Kconfig.kexec
mips/kexec: refactor for kernel/Kconfig.kexec
parisc/kexec: refactor for kernel/Kconfig.kexec
powerpc/kexec: refactor for kernel/Kconfig.kexec
riscv/kexec: refactor for kernel/Kconfig.kexec
s390/kexec: refactor for kernel/Kconfig.kexec
sh/kexec: refactor for kernel/Kconfig.kexec

arch/Kconfig | 13 -----
arch/arm/Kconfig | 29 ++---------
arch/arm64/Kconfig | 62 +++++------------------
arch/ia64/Kconfig | 28 ++---------
arch/loongarch/Kconfig | 26 +++-------
arch/m68k/Kconfig | 19 +------
arch/mips/Kconfig | 32 ++----------
arch/parisc/Kconfig | 34 +++++--------
arch/powerpc/Kconfig | 55 +++++++--------------
arch/riscv/Kconfig | 48 ++++++------------
arch/s390/Kconfig | 65 +++++++-----------------
arch/sh/Kconfig | 46 +++--------------
arch/x86/Kconfig | 89 +++++----------------------------
init/Kconfig | 2 +
kernel/Kconfig.kexec | 110 +++++++++++++++++++++++++++++++++++++++++
15 files changed, 229 insertions(+), 429 deletions(-)
create mode 100644 kernel/Kconfig.kexec

--
2.31.1

2023-06-19 15:05:48

by Eric DeVolder

[permalink] [raw]

Subject: [PATCH v2 06/13] loongarch/kexec: refactor for kernel/Kconfig.kexec

2023-06-19 15:05:48

by Eric DeVolder

[permalink] [raw]

Subject: [PATCH v2 13/13] sh/kexec: refactor for kernel/Kconfig.kexec

2023-06-19 15:06:10

by Eric DeVolder

[permalink] [raw]

Subject: [PATCH v2 05/13] arm64/kexec: refactor for kernel/Kconfig.kexec

The kexec and crash kernel options are provided in the common
kernel/Kconfig.kexec. Utilize the common options and provide
the ARCH_SUPPORTS_ and ARCH_SELECTS_ entries to recreate the
equivalent set of KEXEC and CRASH options.

Signed-off-by: Eric DeVolder <[email protected]>
---
arch/arm64/Kconfig | 62 +++++++++-------------------------------------
1 file changed, 12 insertions(+), 50 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 343e1e1cae10..dfe47efa7cc1 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1433,60 +1433,22 @@ config PARAVIRT_TIME_ACCOUNTING

If in doubt, say N here.

-config KEXEC
- depends on PM_SLEEP_SMP
- select KEXEC_CORE
- bool "kexec system call"
- help
- kexec is a system call that implements the ability to shutdown your
- current kernel, and to start another kernel. It is like a reboot
- but it is independent of the system firmware. And like a reboot
- you can start any kernel with it, not just Linux.
-
-config KEXEC_FILE
- bool "kexec file based system call"
- select KEXEC_CORE
- select HAVE_IMA_KEXEC if IMA
- help
- This is new version of kexec system call. This system call is
- file based and takes file descriptors as system call argument
- for kernel and initramfs as opposed to list of segments as
- accepted by previous system call.
-
-config KEXEC_SIG
- bool "Verify kernel signature during kexec_file_load() syscall"
- depends on KEXEC_FILE
- help
- Select this option to verify a signature with loaded kernel
- image. If configured, any attempt of loading a image without
- valid signature will fail.
-
- In addition to that option, you need to enable signature
- verification for the corresponding kernel image type being
- loaded in order for this to work.
+config ARCH_SUPPORTS_KEXEC
+ def_bool PM_SLEEP_SMP

-config KEXEC_IMAGE_VERIFY_SIG
- bool "Enable Image signature verification support"
- default y
- depends on KEXEC_SIG
- depends on EFI && SIGNED_PE_FILE_VERIFICATION
- help
- Enable Image signature verification support.
+config ARCH_SUPPORTS_KEXEC_FILE
+ def_bool y

-comment "Support for PE file signature verification disabled"
- depends on KEXEC_SIG
- depends on !EFI || !SIGNED_PE_FILE_VERIFICATION
+config ARCH_SELECTS_KEXEC_FILE
+ def_bool y
+ depends on KEXEC_FILE
+ select HAVE_IMA_KEXEC if IMA

-config CRASH_DUMP
- bool "Build kdump crash kernel"
- help
- Generate crash dump after being started by kexec. This should
- be normally only set in special crash dump kernels which are
- loaded in the main kernel with kexec-tools into a specially
- reserved region and then later executed after a crash by
- kdump/kexec.
+config ARCH_DEFAULT_KEXEC_IMAGE_VERIFY_SIG
+ def_bool y

- For more details see Documentation/admin-guide/kdump/kdump.rst
+config ARCH_SUPPORTS_CRASH_DUMP
+ def_bool y

config TRANS_TABLE
def_bool y
--
2.31.1

2023-06-19 15:06:15

by Eric DeVolder

[permalink] [raw]

Subject: [PATCH v2 11/13] riscv/kexec: refactor for kernel/Kconfig.kexec

2023-06-19 15:06:23

by Eric DeVolder

[permalink] [raw]

Subject: [PATCH v2 03/13] arm/kexec: refactor for kernel/Kconfig.kexec

2023-06-19 15:06:28

by Eric DeVolder

[permalink] [raw]

Subject: [PATCH v2 02/13] x86/kexec: refactor for kernel/Kconfig.kexec

The kexec and crash kernel options are provided in the common
kernel/Kconfig.kexec. Utilize the common options and provide
the ARCH_SUPPORTS_ and ARCH_SELECTS_ entries to recreate the
equivalent set of KEXEC and CRASH options.

Signed-off-by: Eric DeVolder <[email protected]>
---
arch/x86/Kconfig | 89 +++++++-----------------------------------------
1 file changed, 13 insertions(+), 76 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 53bab123a8ee..1afc6ca2986b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2043,88 +2043,25 @@ config EFI_RUNTIME_MAP

source "kernel/Kconfig.hz"

-config KEXEC
- bool "kexec system call"
- select KEXEC_CORE
- help
- kexec is a system call that implements the ability to shutdown your
- current kernel, and to start another kernel. It is like a reboot
- but it is independent of the system firmware. And like a reboot
- you can start any kernel with it, not just Linux.
-
- The name comes from the similarity to the exec system call.
-
- It is an ongoing process to be certain the hardware in a machine
- is properly shutdown, so do not be surprised if this code does not
- initially work for you. As of this writing the exact hardware
- interface is strongly in flux, so no good recommendation can be
- made.
-
-config KEXEC_FILE
- bool "kexec file based system call"
- select KEXEC_CORE
- select HAVE_IMA_KEXEC if IMA
- depends on X86_64
- depends on CRYPTO=y
- depends on CRYPTO_SHA256=y
- help
- This is new version of kexec system call. This system call is
- file based and takes file descriptors as system call argument
- for kernel and initramfs as opposed to list of segments as
- accepted by previous system call.
+config ARCH_SUPPORTS_KEXEC
+ def_bool y

-config ARCH_HAS_KEXEC_PURGATORY
- def_bool KEXEC_FILE
+config ARCH_SUPPORTS_KEXEC_FILE
+ def_bool X86_64 && CRYPTO && CRYPTO_SHA256

-config KEXEC_SIG
- bool "Verify kernel signature during kexec_file_load() syscall"
+config ARCH_SELECTS_KEXEC_FILE
+ def_bool y
depends on KEXEC_FILE
- help
-
- This option makes the kexec_file_load() syscall check for a valid
- signature of the kernel image. The image can still be loaded without
- a valid signature unless you also enable KEXEC_SIG_FORCE, though if
- there's a signature that we can check, then it must be valid.
-
- In addition to this option, you need to enable signature
- verification for the corresponding kernel image type being
- loaded in order for this to work.
-
-config KEXEC_SIG_FORCE
- bool "Require a valid signature in kexec_file_load() syscall"
- depends on KEXEC_SIG
- help
- This option makes kernel signature verification mandatory for
- the kexec_file_load() syscall.
+ select HAVE_IMA_KEXEC if IMA

-config KEXEC_BZIMAGE_VERIFY_SIG
- bool "Enable bzImage signature verification support"
- depends on KEXEC_SIG
- depends on SIGNED_PE_FILE_VERIFICATION
- select SYSTEM_TRUSTED_KEYRING
- help
- Enable bzImage signature verification support.
+config ARCH_HAS_KEXEC_PURGATORY
+ def_bool KEXEC_FILE

-config CRASH_DUMP
- bool "kernel crash dumps"
- depends on X86_64 || (X86_32 && HIGHMEM)
- help
- Generate crash dump after being started by kexec.
- This should be normally only set in special crash dump kernels
- which are loaded in the main kernel with kexec-tools into
- a specially reserved region and then later executed after
- a crash by kdump/kexec. The crash dump kernel must be compiled
- to a memory address not used by the main kernel or BIOS using
- PHYSICAL_START, or it must be built as a relocatable image
- (CONFIG_RELOCATABLE=y).
- For more details see Documentation/admin-guide/kdump/kdump.rst
+config ARCH_SUPPORTS_KEXEC_JUMP
+ def_bool y

-config KEXEC_JUMP
- bool "kexec jump"
- depends on KEXEC && HIBERNATION
- help
- Jump between original kernel and kexeced kernel and invoke
- code in physical address mode via KEXEC
+config ARCH_SUPPORTS_CRASH_DUMP
+ def_bool X86_64 || (X86_32 && HIGHMEM)

config PHYSICAL_START
hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
--
2.31.1

2023-06-19 15:07:09

by Eric DeVolder

[permalink] [raw]

Subject: [PATCH v2 10/13] powerpc/kexec: refactor for kernel/Kconfig.kexec

The kexec and crash kernel options are provided in the common
kernel/Kconfig.kexec. Utilize the common options and provide
the ARCH_SUPPORTS_ and ARCH_SELECTS_ entries to recreate the
equivalent set of KEXEC and CRASH options.

Signed-off-by: Eric DeVolder <[email protected]>
Reviewed-by: Sourabh Jain <[email protected]>
---
arch/powerpc/Kconfig | 55 ++++++++++++++------------------------------
1 file changed, 17 insertions(+), 38 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index bff5820b7cda..70edbda08ae3 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -588,41 +588,21 @@ config PPC64_SUPPORTS_MEMORY_FAILURE
default "y" if PPC_POWERNV
select ARCH_SUPPORTS_MEMORY_FAILURE

-config KEXEC
- bool "kexec system call"
- depends on PPC_BOOK3S || PPC_E500 || (44x && !SMP)
- select KEXEC_CORE
- help
- kexec is a system call that implements the ability to shutdown your
- current kernel, and to start another kernel. It is like a reboot
- but it is independent of the system firmware. And like a reboot
- you can start any kernel with it, not just Linux.
-
- The name comes from the similarity to the exec system call.
-
- It is an ongoing process to be certain the hardware in a machine
- is properly shutdown, so do not be surprised if this code does not
- initially work for you. As of this writing the exact hardware
- interface is strongly in flux, so no good recommendation can be
- made.
-
-config KEXEC_FILE
- bool "kexec file based system call"
- select KEXEC_CORE
- select HAVE_IMA_KEXEC if IMA
- select KEXEC_ELF
- depends on PPC64
- depends on CRYPTO=y
- depends on CRYPTO_SHA256=y
- help
- This is a new version of the kexec system call. This call is
- file based and takes in file descriptors as system call arguments
- for kernel and initramfs as opposed to a list of segments as is the
- case for the older kexec call.
+config ARCH_SUPPORTS_KEXEC
+ def_bool PPC_BOOK3S || PPC_E500 || (44x && !SMP)
+
+config ARCH_SUPPORTS_KEXEC_FILE
+ def_bool PPC64 && CRYPTO=y && CRYPTO_SHA256=y

config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE

+config ARCH_SELECTS_KEXEC_FILE
+ def_bool y
+ depends on KEXEC_FILE
+ select KEXEC_ELF
+ select HAVE_IMA_KEXEC if IMA
+
config PPC64_BIG_ENDIAN_ELF_ABI_V2
bool "Build big-endian kernel using ELF ABI V2 (EXPERIMENTAL)"
depends on PPC64 && CPU_BIG_ENDIAN
@@ -682,14 +662,13 @@ config RELOCATABLE_TEST
loaded at, which tends to be non-zero and therefore test the
relocation code.

-config CRASH_DUMP
- bool "Build a dump capture kernel"
- depends on PPC64 || PPC_BOOK3S_32 || PPC_85xx || (44x && !SMP)
+config ARCH_SUPPORTS_CRASH_DUMP
+ def_bool PPC64 || PPC_BOOK3S_32 || PPC_85xx || (44x && !SMP)
+
+config ARCH_SELECTS_CRASH_DUMP
+ def_bool y
+ depends on CRASH_DUMP
select RELOCATABLE if PPC64 || 44x || PPC_85xx
- help
- Build a kernel suitable for use as a dump capture kernel.
- The same kernel binary can be used as production kernel and dump
- capture kernel.

config FA_DUMP
bool "Firmware-assisted dump"
--
2.31.1

2023-06-19 15:07:18

by Eric DeVolder

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Subject: [PATCH v2 08/13] mips/kexec: refactor for kernel/Kconfig.kexec

2023-06-19 15:17:46

by Eric DeVolder

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Subject: [PATCH v2 04/13] ia64/kexec: refactor for kernel/Kconfig.kexec

2023-06-19 18:42:05

by John Paul Adrian Glaubitz

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Subject: Re: [PATCH v2 13/13] sh/kexec: refactor for kernel/Kconfig.kexec

Hi Eric!

On Mon, 2023-06-19 at 10:58 -0400, Eric DeVolder wrote:
> The kexec and crash kernel options are provided in the common
> kernel/Kconfig.kexec. Utilize the common options and provide
> the ARCH_SUPPORTS_ and ARCH_SELECTS_ entries to recreate the
> equivalent set of KEXEC and CRASH options.
>
> Signed-off-by: Eric DeVolder <[email protected]>
> ---
> arch/sh/Kconfig | 46 ++++++++--------------------------------------
> 1 file changed, 8 insertions(+), 38 deletions(-)
>
> diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
> index 9652d367fc37..d52e0beed7e9 100644
> --- a/arch/sh/Kconfig
> +++ b/arch/sh/Kconfig
> @@ -546,44 +546,14 @@ menu "Kernel features"
>
> source "kernel/Kconfig.hz"
>
> -config KEXEC
> - bool "kexec system call (EXPERIMENTAL)"
> - depends on MMU
> - select KEXEC_CORE
> - help
> - kexec is a system call that implements the ability to shutdown your
> - current kernel, and to start another kernel. It is like a reboot
> - but it is independent of the system firmware. And like a reboot
> - you can start any kernel with it, not just Linux.
> -
> - The name comes from the similarity to the exec system call.
> -
> - It is an ongoing process to be certain the hardware in a machine
> - is properly shutdown, so do not be surprised if this code does not
> - initially work for you. As of this writing the exact hardware
> - interface is strongly in flux, so no good recommendation can be
> - made.
> -
> -config CRASH_DUMP
> - bool "kernel crash dumps (EXPERIMENTAL)"
> - depends on BROKEN_ON_SMP
> - help
> - Generate crash dump after being started by kexec.
> - This should be normally only set in special crash dump kernels
> - which are loaded in the main kernel with kexec-tools into
> - a specially reserved region and then later executed after
> - a crash by kdump/kexec. The crash dump kernel must be compiled
> - to a memory address not used by the main kernel using
> - PHYSICAL_START.
> -
> - For more details see Documentation/admin-guide/kdump/kdump.rst
> -
> -config KEXEC_JUMP
> - bool "kexec jump (EXPERIMENTAL)"
> - depends on KEXEC && HIBERNATION
> - help
> - Jump between original kernel and kexeced kernel and invoke
> - code via KEXEC
> +config ARCH_SUPPORTS_KEXEC
> + def_bool MMU
> +
> +config ARCH_SUPPORTS_CRASH_DUMP
> + def_bool BROKEN_ON_SMP
> +
> +config ARCH_SUPPORTS_KEXEC_JUMP
> + def_bool y
>
> config PHYSICAL_START
> hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)

Acked-by: John Paul Adrian Glaubitz <[email protected]>

--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer
`. `' Physicist
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913

2023-06-20 09:07:04

by Baoquan He

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Subject: Re: [PATCH v2 02/13] x86/kexec: refactor for kernel/Kconfig.kexec

Hi Eric,

On 06/19/23 at 10:57am, Eric DeVolder wrote:
......
> +config ARCH_SUPPORTS_KEXEC
> + def_bool y
>
> -config ARCH_HAS_KEXEC_PURGATORY
> - def_bool KEXEC_FILE
> +config ARCH_SUPPORTS_KEXEC_FILE
> + def_bool X86_64 && CRYPTO && CRYPTO_SHA256
......
> +config ARCH_SELECTS_KEXEC_FILE
> + def_bool y
> depends on KEXEC_FILE
> - help

I am a little confused about this ARCH_SELECTS_XX adding. Wondering what
limits us defining the ARCH_SUPPORTS_KEXEC_FILE like below? I have limited
knowledge about Kconfig, please correct me if I am wrong. Thanks in
advance.

+config ARCH_SUPPORTS_KEXEC_FILE
+ def_bool y
depends on KEXEC_FILE
depends on X86_64 && CRYPTO && CRYPTO_SHA256

> -
> - This option makes the kexec_file_load() syscall check for a valid
> - signature of the kernel image. The image can still be loaded without
> - a valid signature unless you also enable KEXEC_SIG_FORCE, though if
> - there's a signature that we can check, then it must be valid.
> -
> - In addition to this option, you need to enable signature
> - verification for the corresponding kernel image type being
> - loaded in order for this to work.
> -

2023-06-20 13:16:22

by Thomas Bogendoerfer

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Subject: Re: [PATCH v2 08/13] mips/kexec: refactor for kernel/Kconfig.kexec

On Mon, Jun 19, 2023 at 10:57:56AM -0400, Eric DeVolder wrote:
> The kexec and crash kernel options are provided in the common
> kernel/Kconfig.kexec. Utilize the common options and provide
> the ARCH_SUPPORTS_ and ARCH_SELECTS_ entries to recreate the
> equivalent set of KEXEC and CRASH options.
>
> Signed-off-by: Eric DeVolder <[email protected]>
> ---
> arch/mips/Kconfig | 32 +++++---------------------------
> 1 file changed, 5 insertions(+), 27 deletions(-)

Acked-by: Thomas Bogendoerfer <[email protected]>

--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]

2023-06-20 13:16:49

by Eric DeVolder

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Subject: Re: [PATCH v2 02/13] x86/kexec: refactor for kernel/Kconfig.kexec

On 6/20/23 03:21, Baoquan He wrote:
> Hi Eric,
>
> On 06/19/23 at 10:57am, Eric DeVolder wrote:
> ......
>> +config ARCH_SUPPORTS_KEXEC
>> + def_bool y
>>
>> -config ARCH_HAS_KEXEC_PURGATORY
>> - def_bool KEXEC_FILE
>> +config ARCH_SUPPORTS_KEXEC_FILE
>> + def_bool X86_64 && CRYPTO && CRYPTO_SHA256
> ......
>> +config ARCH_SELECTS_KEXEC_FILE
>> + def_bool y
>> depends on KEXEC_FILE
>> - help
>
> I am a little confused about this ARCH_SELECTS_XX adding. Wondering what
> limits us defining the ARCH_SUPPORTS_KEXEC_FILE like below? I have limited
> knowledge about Kconfig, please correct me if I am wrong. Thanks in
> advance.
>
> +config ARCH_SUPPORTS_KEXEC_FILE
> + def_bool y
> depends on KEXEC_FILE
> depends on X86_64 && CRYPTO && CRYPTO_SHA256
>

For the ARCH_SUPPORTS_ options, I chose to list the dependencies on the def_bool line to show that
it took all those conditions to result in True.
However, as you point out, using a def_bool y and then listing them as 'depends on' works as well.
Probably would have resulted in fewer changes to the Kconfig file.
Either way is ok (the 'depends on KEXEC_FILE' is erroneous in your example).
eric

>> -
>> - This option makes the kexec_file_load() syscall check for a valid
>> - signature of the kernel image. The image can still be loaded without
>> - a valid signature unless you also enable KEXEC_SIG_FORCE, though if
>> - there's a signature that we can check, then it must be valid.
>> -
>> - In addition to this option, you need to enable signature
>> - verification for the corresponding kernel image type being
>> - loaded in order for this to work.
>> -
>

2023-06-20 14:59:56

by Baoquan He

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Subject: Re: [PATCH v2 02/13] x86/kexec: refactor for kernel/Kconfig.kexec

On 06/20/23 at 07:56am, Eric DeVolder wrote:
>
>
> On 6/20/23 03:21, Baoquan He wrote:
> > Hi Eric,
> >
> > On 06/19/23 at 10:57am, Eric DeVolder wrote:
> > ......
> > > +config ARCH_SUPPORTS_KEXEC
> > > + def_bool y
> > > -config ARCH_HAS_KEXEC_PURGATORY
> > > - def_bool KEXEC_FILE
> > > +config ARCH_SUPPORTS_KEXEC_FILE
> > > + def_bool X86_64 && CRYPTO && CRYPTO_SHA256
> > ......
> > > +config ARCH_SELECTS_KEXEC_FILE
> > > + def_bool y
> > > depends on KEXEC_FILE
> > > - help
> >
> > I am a little confused about this ARCH_SELECTS_XX adding. Wondering what
> > limits us defining the ARCH_SUPPORTS_KEXEC_FILE like below? I have limited
> > knowledge about Kconfig, please correct me if I am wrong. Thanks in
> > advance.
> >
> > +config ARCH_SUPPORTS_KEXEC_FILE
> > + def_bool y
> > depends on KEXEC_FILE
> > depends on X86_64 && CRYPTO && CRYPTO_SHA256
> >
>
> For the ARCH_SUPPORTS_ options, I chose to list the dependencies on the
> def_bool line to show that it took all those conditions to result in True.
> However, as you point out, using a def_bool y and then listing them as 'depends on' works as well.
> Probably would have resulted in fewer changes to the Kconfig file.
> Either way is ok (the 'depends on KEXEC_FILE' is erroneous in your example).

Got it, thanks. To me, one option with explicit dependencies looks clearer
and straightforward. I need check and investigage why two options are needed,
whether two options are unavoidable. Not sure if other people would get
the same feeling or not. Honestly, it's my first time to see the usage of
XXX_SELECTS_XXX, it took me a while to dig into.

>
> > > -
> > > - This option makes the kexec_file_load() syscall check for a valid
> > > - signature of the kernel image. The image can still be loaded without
> > > - a valid signature unless you also enable KEXEC_SIG_FORCE, though if
> > > - there's a signature that we can check, then it must be valid.
> > > -
> > > - In addition to this option, you need to enable signature
> > > - verification for the corresponding kernel image type being
> > > - loaded in order for this to work.
> > > -
> >
>

2023-06-20 15:18:12

by Eric DeVolder

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Subject: Re: [PATCH v2 13/13] sh/kexec: refactor for kernel/Kconfig.kexec

On 6/19/23 13:21, John Paul Adrian Glaubitz wrote:
> Acked-by: John Paul Adrian Glaubitz<[email protected]>

Thank you!
eric

2023-06-20 15:36:47

by Eric DeVolder

[permalink] [raw]

Subject: Re: [PATCH v2 08/13] mips/kexec: refactor for kernel/Kconfig.kexec

On 6/20/23 07:52, Thomas Bogendoerfer wrote:
> Acked-by: Thomas Bogendoerfer<[email protected]>

Thank you!
eric